机型:北京牌8303型。故障现象:黑白图像与伴音正常,无彩色。分析与检修:荧光屏能显示出正常的黑白图像,表明亮度通道和末级视放基本正常。无彩色,表明色度信号处理电路有故障。该机选用IC501(TA7193P)为色解码电路,(21)脚是消色检波输出滤波引出端,在正常接收彩色电视信号时,(21)脚钳位在6.5V左右,消色放大电路末级处于截止状态,(20)脚在色饱和度电位器R_(555) Model: Beijing card 8303 type. Symptoms: black and white images and sound normal, no color. Analysis and Overhaul: Fluorescent screen can display normal black and white images, indicating that the brightness channel and the final stage of playing basically normal. No color, indicating that the chrominance signal processing circuit is faulty. This machine chooses IC501 (TA7193P) as the color decipher circuit, the foot of (21) is the achromatic wave output filter leading-out end, when the color television signal is received normally, the clamp of (21) feet is about 6.5V, Is off, (20) feet in the color saturation potentiometer R_ (555)